Electric motor including a rotor

ABSTRACT

An electric motor includes a rotor having a rotor shaft part and a first shaft part and a second shaft part. The rotor shaft is situated axially between the first and the second shaft parts. The first shaft part includes a first bearing seat and is connected to the rotor shaft part in a torsionally fixed manner, and the second shaft part includes a second bearing seat and is connected to the rotor shaft part in a torsionally fixed manner.

FIELD OF THE INVENTION

The present invention relates to an electric motor including a rotor.

BACKGROUND INFORMATION

It is conventional for an electric motor to have a rotatably mountedrotor.

SUMMARY

Example embodiments of the present invention provide for an electricmotor in many variants to be produced in a cost-effective manner.

According to example embodiments of the present invention, an electricmotor includes a rotor having a rotor shaft part and a first shaft partand a second shaft part. The rotor shaft part is axially situatedbetween the first and the second shaft parts. The first shaft part has afirst bearing seat and is connected to the rotor shaft part in atorsionally fixed manner, and the second shaft part has a second bearingseat and is connected to the rotor shaft part in a torsionally fixedmanner.

This has the advantage that the rotor is made up of a plurality ofparts. Thus, a high variety of rotors is able to be produced using a lownumber of parts. In these variants, the rotor is therefore able to beoffered at the axially front end region with different options. Forexample, the first shaft part may be arranged to be larger or smaller,which means that a pinion having different sizes may be attached. In thesame manner, the second shaft part may be arranged to include aconnection section for a fan and/or a brake, or it may be provided withor without an extension section.

According to example embodiments, the rotor is mounted via a firstbearing in a first bearing shield and via a second bearing in a secondbearing shield, the first and the second bearing shields being connectedto a stator housing which is situated between the first and the secondbearing shields. This has the advantage that the mounting of the rotoris able to be carried out on the two shaft parts and a high transversemoment is therefore derivable. In addition, minimal distortions areapplied to the rotor shaft part itself. Moreover, bearings of differentsizes may be provided.

According to example embodiments, a first bearing of the rotor issituated on the first bearing seat and a second bearing of the rotor issituated on the second bearing seat. The first bearing is accommodatedin the first bearing shield and the second bearing is accommodated inthe second bearing shield. This offers the advantage that anuncomplicated production is possible, and because of the tripartiteconfiguration of the housing, i.e. the stator housing part and two endshields, different axially front or rear mechanical interfaces areprovidable using a small number of parts, resulting in a high variety ofmotors.

According to example embodiments, a laminated stator core having astator winding inserted therein is accommodated in the stator housing.This has the advantage that the stator winding is able to be provided asa three-phase winding, which allows a rotary field to be generated. Therotor has a squirrel cage so that the electric motor is an asynchronousmotor.

According to example embodiments, the first shaft part has a firstjournal region, which is pressed into a first recess of the rotor shaftpart, and the second shaft part has a second journal region, which ispressed into a second recess of the rotor shaft part. This offers theadvantage that a centered, torsion-proof connection of the shaft partsto the rotor shaft part is able to be established.

According to example embodiments, the first journal region has agear-tooth region, i.e. a region provided with teeth, and a cylindricalregion, the gear-tooth region being pressed into a region, provided withinternal teeth, of the first recess, in particular under an elasticdeformation, and/or the second journal region also has a gear-toothregion, i.e. a region provided with teeth, and a cylindrical region, thegear-tooth region being pressed into a region, provided with internalteeth, of the second recess, in particular under an elastic deformation.This has the advantage of achieving a torque-proof connection which isable to withstand particularly high stresses.

According to example embodiments, the rotor shaft packet is situated onthe rotor, and the contact region between the laminated rotor core andthe rotor shaft part has an axially smaller extension than the laminatedrotor core. This offers the advantage that gaps may be provided axiallyon both sides, which protect the laminated rotor core from axiallyintroduced distortions, in particular from the area of the connection ofthe journal regions to the rotor shaft part.

According to example embodiments, a first gap, which is axially adjacentto the contact region, is situated between the laminated rotor core andthe rotor shaft part, and/or a second first gap, which is axiallyadjacent to the contact region, is situated between the laminated rotorcore and the rotor shaft part. This has the advantage that the contactregion, i.e. the support region, is protected from distortionsintroduced by connection interfaces, and consequently retains itscylindrical outer contour without change.

According to example embodiments, the journal region of the first shaftpart is axially set apart from the contact region, and/or the journalregion of the second shaft part is axially set apart from the contactregion. This has the advantage that no substantial distortions aretransmitted from the journal region to the contact region despite thejournal region being pressed into the internal toothing provided on therotor shaft part and despite the introduction of high forces during thispress-in operation.

According to example embodiments, the axial region covered by thejournal region of the first shaft part overlaps with the axial regioncovered by the first gap and/or is set apart from the axial regioncovered by the contact region, and/or the axial region covered by thejournal region of the second shaft part overlaps with the axial regioncovered by the second gap and/or is set apart from the axial regioncovered by the contact region. This has the advantage that no harmfuldistortions, which would cause a deformation of the contact region,reach the contact region.

According to example embodiments, a squirrel cage is accommodated in thelaminated rotor core. This offers the advantage that the motor is ableto be arranged as an asynchronous motor.

According to example embodiments, the first shaft part has a connectionarea, which particularly has a feather key groove for the connection toa gear-tooth part, in particular a pinion. This is consideredadvantageous insofar as the motor may be used for driving atransmission.

According to example embodiments, the second shaft part has a connectionarea, which particularly has a feather key groove for the connection toa fan wheel and/or a driver. This is considered advantageous insofar asthe motor is able to be arranged as a brake motor or a fan motor.

Further features and aspects of example embodiments of the presentinvention are described in greater detail below with reference to theappended Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view through an electric motoraccording to an example embodiment of the present invention, theelectric motor having a rotor which includes a rotor shaft part 9, afirst shaft part 8 and a second shaft part 12.

FIG. 2 is a side view of the rotor, in which a laminated rotor core 4together with a squirrel cage 3 which are situated on rotor shaft part 9are illustrated in a partial cross-sectional view.

FIG. 3 is a perspective view of a second shaft part 12.

FIG. 4 is a perspective view of a first shaft part 8.

FIG. 5 illustrates the rotor of an exemplary embodiment, which resemblesthe rotor of the exemplary embodiment illustrated in FIGS. 1 to 4, rotorshaft part 9 being shown in a partial cross-sectional view.

DETAILED DESCRIPTION

As illustrated in FIGS. 1 to 4, the motor has a stator housing 1, inwhich a laminated stator core 2 which accommodates the stator winding issituated. Winding head 5 axially projects on both sides from the axialregion covered by laminated stator core 2.

Stator housing 1 is connected at its first axial end region to a bearingshield 6, which accommodates a first bearing 7 for the mounting of therotor.

Stator housing 1 is connected at its other axial end region to a bearingshield 10, which accommodates a second bearing 11 for the mounting ofthe rotor.

The rotor is formed by a rotor shaft part 9, which has an axiallydirected stepped bore at its two axial end regions, into which a journalregion formed on first shaft part 8 and on second shaft part 12 isinserted in each case.

First shaft part 8 has a bearing seat 22 on which first bearing 7 issituated. In addition, the journal region of first shaft part 8 issituated in the axial end region, facing rotor shaft part 9, of firstshaft part 8. The journal region is provided with a gear-tooth region 41and a cylindrical region 40, which is situated between gear-tooth region41 and bearing seat 22.

Provided in the other axial end region of first shaft part 8 is aconnection area 23, which has a feather key groove so that a gear-toothpart, in particular a pinion, is connectable in a torsionally fixedmanner to connection area 23 with the aid of the feather key connection.

Second shaft part 12 has a bearing seat 24 on which second bearing 11 isdisposed. In addition, the journal region of second shaft part 12 issituated in the axial end region, facing rotor shaft part 9, of firstshaft part 8. The journal region has a gear-tooth region 31 and acylindrical region 30 which is disposed between gear-tooth region 31 andbearing seat 24.

Provided in the other axial end region of second shaft part 12 is aconnection area 20, which has a feather key groove so that a fan isconnectable in a torsion-proof manner to connection area 20 with the aidof the feather key connection. Alternatively or additionally, it is alsopossible to connect an angle sensor here for the detection of theangular position of the rotor.

A clearance region 21 is situated between bearing seat 24 and connectionarea 20. It, too, may optionally be provided with a feather key grooveso that a gear-tooth part, in particular a driver, is able to beconnected to shaft part 12 in a keyed manner. A brake lining support ofan electromagnetically actuable brake may be placed on the gear-toothpart, which is disposed in a torsion-proof manner with respect to therotor but is axially displaceable.

Gear-tooth regions 31 and 41 are able to be arranged as axially formedtoothing and/or as knurled regions in each case, i.e. in particular suchthat the toothing is arranged as knurling.

The respective stepped bore has a cylindrical region in which therespective cylindrical region (30, 40) is accommodated, and a regionprovided with an internal toothing into which the respective gear-toothregion (31, 41) is pressed. However, this press-in operation resultsonly in an elastic deformation and thus in no chip formation.

The cylindrical region (30, 40) may have a greater axial length than thegear-tooth regions (31, 41). As a result, the respective cylindricalregion (30, 40) guides and centers the individual shaft part (8, 12)when the gear-toothed regions (31, 41) are pressed in into therespective region provided with an external toothing.

Bearing seat 24 of second shaft part 12 has a larger diameter thangear-tooth region 31 situated axially adjacent to it. Bearing seat 24 ofthe second shaft part has a larger diameter than clearance region 21,which is situated on the side of bearing seat 24 that faces axially awayfrom gear-tooth region 31.

Clearance region 21 has a larger diameter than connection area 20.

Bearing seat 22 of first shaft part 8 has a larger diameter thangear-tooth region 41 situated axially adjacent to it. Bearing seat 22 offirst shaft part 8 has a larger diameter than connection area 23, whichis on the side of bearing seat 22 that faces axially away fromgear-tooth region 41.

Laminated rotor core 4 is attached to rotor shaft part 9. However, thearea of contact, i.e. the contact region, between laminated rotor core 4and rotor shaft part 9 has a smaller axial extension than laminatedrotor core 4.

This is so because rotor shaft part 9 has a larger diameter in thecontact region than in the axially adjoining regions of rotor shaft part9 on both sides. As a result, a gap (15, 16) is provided in theseadjoining regions between laminated rotor core 4 and rotor shaft part 9.

Squirrel cage 3 may be made from aluminum and/or copper.

Laminated rotor core 4 may be made up of a stack of individual sheetmetal parts, which is formed in an axial direction, the sheet metalparts being produced from sheet steel, for example.

The region axially covered by the respective stepped bore is set apartfrom the region axially covered by the contact region. As a result, anaxial clearance is provided between the stepped bore and the contactregion.

However, the region axially covered by the respective stepped bore mustnot overlap with the axial region covered by the respective adjacent gap(15, 16). In any event, even then an axial clearance between the steppedbore and the contact region of laminated rotor core 4 and rotor shaftpart 9 is present, however.

In this manner, stresses that may possibly arise when shaft parts 8 and12 are joined to rotor shaft part 9 are kept away as much as possiblefrom the contact region where it is important for rotor shaft part 9 tohave the most precise cylindrical outer contour possible.

Moreover, in the event that shaft parts 8 and 12 do not align with rotorshaft part 9 with sufficient precision, retroactive working and thusaligning of shaft parts 8 and 12 with respect to rotor shaft part 9 ispossible, without the stresses that occur in the process having aninterfering effect on laminated rotor core 4 accommodated in the contactregion.

Laminated rotor core 4 may be thermally shrunk onto the contact region,i.e. connected in a nonpositive manner.

First shaft part 8 rests against cutting edge 13 of rotor shaft part 9via the step formed at the base of the journal region.

Second shaft part 12 rests against cutting edge 14 of rotor shaft part 9via the step formed at the base of the journal region.

Because the rotor is made up of multiple parts, a high variety of rotorsis able to be made available using a small number of components.

As illustrated by the similar rotor according to FIG. 5, cylindricalregion 40 of the journal region of first shaft part 8 and gear-toothregion 41 of the journal region of first shaft part 8 are set apart by agap 16 in each case, which is axially interposed between cylindricalregion 40 and the contact region of laminated stator core 4 and rotorshaft part 9.

In the same manner, cylindrical region 30 of the journal region ofsecond shaft part 12 and gear-tooth region 31 of the journal region ofsecond shaft part 12 are set apart by a gap 15 in each case, which isaxially interposed between cylindrical region 30 and the contact regionof laminated stator core 4 and rotor shaft part 9.

The contact region thus functions as a support region for laminatedrotor core 4.

First shaft part 8 is made of steel. Second shaft part 12 is made ofsteel. First rotor shaft part 9 is made of steel.

In further exemplary embodiments according to the present invention, thecylindrical regions (30, 40) of the journal regions and/or thegear-tooth regions (31, 41) are additionally provided with a spiralgroove. In this manner, the air that is compressed when the journalregions are pressed into the stepped bore is able to escape, which thusmakes it easier to ensure the centering during the press-in operation.

LIST OF REFERENCE NUMERALS

1 stator housing

2 laminated stator core

3 squirrel cage

4 laminated rotor core

5 winding head

6 bearing shield

7 bearing

8 first shaft part

9 rotor shaft part

10 bearing shield

11 bearing

12 second shaft part

13 cutting edge

14 cutting edge

15 gap

16 gap

20 connection area

21 clearance region

22 bearing seat

23 connection area

24 bearing seat

30 cylindrical region of the journal region

31 gear-tooth region of the journal region

40 cylindrical region of the journal region

41 gear-tooth region of the journal region

1-13. (canceled)
 14. An electric motor, comprising: a rotor including: arotor shaft part; a first shaft part; and a second shaft part; whereinthe rotor shaft part is arranged axially between the first shaft partand the second shaft part; wherein the first shaft part has a firstbearing seat and is connected to the rotor shaft part in a torsionallyfixed manner; and wherein the second shaft part has a second bearingseat and is connected to the rotor shaft part in a torsionally fixedmanner.
 15. The electric motor according to claim 14, wherein the rotoris mounted via a first bearing in a first bearing shield and via asecond bearing in a second bearing shield, the first and the secondbearing shields being connected to a stator housing, which is arrangedbetween the first bearing shield and the second bearing shield.
 16. Theelectric motor according to claim 15, wherein a first bearing of therotor is arranged on the first bearing seat and a second bearing of therotor is arranged on the second bearing seat, the first bearing beingaccommodated in the first bearing shield and the second bearing beingaccommodated in the second bearing shield.
 17. The electric motoraccording to claim 15, wherein a laminated stator core having a statorwinding inserted therein is accommodated in the stator housing.
 18. Theelectric motor according to claim 14, wherein the first shaft part has afirst journal region pressed into a first recess of the rotor shaftpart, and the second shaft part has a second journal region pressed intoa second recess of the rotor shaft part.
 19. The electric motoraccording to claim 18, wherein the first journal region has a gear-toothregion and a cylindrical region, the gear-tooth region of the firstjournal region being pressed into a region, provided with internalteeth, of the first recess, and/or the second journal region has agear-tooth region and a cylindrical region, the gear-tooth region of thesecond journal region being pressed into a region, provided withinternal teeth, of the second recess.
 20. The electric motor accordingto claim 19, wherein the gear-tooth region of the first journal regionis pressed into the region of the first recess under elasticdeformation, and/or the gear-tooth region of the second journal regionis pressed into the region of the second recess under elasticdeformation.
 21. The electric motor according to claim 14, wherein alaminated rotor core is provided on the rotor, and a contact regionbetween the laminated rotor core and the rotor shaft part has a smalleraxial extension than the laminated rotor core.
 22. The electric motoraccording to claim 21, wherein a first gap, which is axially adjacent tothe contact region, is provided between the laminated rotor core and thefirst shaft part, and/or a second gap, which is axially adjacent to thecontact region, is provided between the laminated rotor core and thesecond shaft part.
 23. The electric motor according to claim 21, whereina journal region of the first shaft part is axially set apart from thecontact region, and/or a journal region of the second shaft part isaxially set apart from the contact region.
 24. The electric motoraccording to claim 18, wherein a laminated rotor core is provided on therotor, a contact region between the laminated rotor core and the rotorshaft part having a smaller axial extension than the laminated rotorcore; and wherein the journal region of the first shaft part is axiallyset apart from the contact region, and/or the journal region of thesecond shaft part is axially set apart from the contact region
 25. Theelectric motor according to claim 22, wherein a laminated rotor core isprovided on the rotor, a contact region between the laminated rotor coreand the rotor shaft part having a smaller axial extension than thelaminated rotor core; and wherein (a) an axial region covered by thejournal region of the first shaft part overlaps with an axial regioncovered by the first gap and/or is set apart from an axial regioncovered by the contact region, and/or (b) an axial region covered by thejournal region of the second shaft part overlaps with an axial regioncovered by the second gap and/or is set apart from the axial regioncovered by the contact region.
 26. The electric motor according to claim21, wherein a squirrel cage is accommodated in the laminated rotor core.27. The electric motor according to claim 14, wherein the first shaftpart has a connection area connecting to a gear-tooth part and/or apinion.
 28. The electric motor according to claim 27, wherein theconnection area includes a feather key groove.
 29. The electric motoraccording to claim 14, wherein the second shaft part has a connectionarea connecting to a fan wheel and/or a driver.
 30. The electric motoraccording to claim 29, wherein the connection area includes a featherkey groove.
 31. The electric motor according to claim 27, wherein thesecond shaft part has a connection area connecting to a fan wheel and/ora driver.